Forming in-situ micro-feature structures with coreless packages

ABSTRACT

Methods of forming a microelectronic packaging structure and associated structures formed thereby are described. Those methods may include attaching a die to a carrier material, forming dielectric material surrounding the die, forming buildup layers in the dielectric material to form a coreless bumpless buildup package structure, and patterning the carrier material to form microchannel structures on the package structure.

RELATED APPLICATION

The present application is a divisional of U.S. patent application No.12/755,183, filed on Apr. 6, 2010, entitled “FORMING IN-SITUMICRO-FEATURE STRUCTURES WITH CORELESS PACKAGES”.

BACKGROUND OF THE INVENTION

As semiconductor technology advances for higher processor performance,advances in packaging architectures may include coreless bumplessbuild-up Layer (BBUL-C) package architectures and other such assemblies.Current process flows for BBUL-C packages involve building of thesubstrate on a temporary core/carrier capped with copper foil, which isetched off after the package is separated from the core. A heat spreadercan be attached post-package manufacturing, which adds additionalmanufacturing cost and time.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming certain embodiments of the present invention,the advantages of this invention can be more readily ascertained fromthe following description of the invention when read in conjunction withthe accompanying drawings in which:

FIGS. 1 a-1 k represent methods of forming structures according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In the following detailed description, reference is made to theaccompanying drawings that show, by way of illustration, specificembodiments in which the invention may be practiced. These embodimentsare described in sufficient detail to enable those skilled in the art topractice the invention. It is to be understood that the variousembodiments of the invention, although different, are not necessarilymutually exclusive. For example, a particular feature, structure, orcharacteristic described herein, in connection with one embodiment, maybe implemented within other embodiments without departing from thespirit and scope of the invention. In addition, it is to be understoodthat the location or arrangement of individual elements within eachdisclosed embodiment may be modified without departing from the spiritand scope of the invention. The following detailed description is,therefore, not to be taken in a limiting sense, and the scope of thepresent invention is defined only by the appended claims, appropriatelyinterpreted, along with the full range of equivalents to which theclaims are entitled. In the drawings, like numerals refer to the same orsimilar functionality throughout the several views.

Methods and associated structures of forming and utilizing amicroelectronic structure, such as a package structure, are described.Those methods may comprise forming a cavity in a plating material tohold a die, attaching the die in the cavity, forming a dielectricmaterial adjacent to the die, forming vias in the dielectric materialadjacent the die, forming interconnects in the vias to form a packagestructure, and patterning the carrier material to form micro-featurestructures on the package structure. Methods of the embodiments enablethe patterning of the copper foil on a carrier material to createmicro-feature structures that can be used as a very effective heatspreader for applications, for example, wherein the die requires heatdissipation.

FIGS. 1 a-1 k illustrate embodiments of methods of forming amicroelectronic structure, such as a package structure, for example.FIG. la illustrates a carrier material 100, 100′. In one embodiment, thecarrier material 100 may comprise a multi-layer copper foil that mayserve as a carrier, such as a microelectronic die carrier. In anembodiment, the carrier material 100 may comprise two layers, 100, 100′as shown, but may comprise one layer or greater than two layers in otherembodiments.

In an embodiment, the carrier material 100 may comprise two layers of aconductive material, such as but not limited to copper, for example,that may be separated by a thin etching barrier (stop) layer 102. In anembodiment, the etch stop layer 102 may comprise such materials asnickel, for example, but may comprise any such material that may serveto comprise an etch stop layer to facilitate the stopping of an etchbetween carrier layers. In an embodiment, the etch stop layer 102 mayserve to aid in the formation of a cavity 104 (FIG. 1 b), especiallyduring an etching process, for example. In an embodiment, a thickness103 of the bottom carrier material layer 100′ may be dictated by thethickness and embedded depth of a die to be embedded into the carriermaterial 100′ in a subsequent assembly step.

The cavity 104 may be formed in one layer of the carrier material, suchas by removing a portion of the bottom carrier material layer 100′. Thecavity 104 may be formed utilizing any suitable removal process, such asan etching process, such as are known in the art. For example, a maskingmaterial may be laminated onto the bottom layer of the carrier material100′ and the carrier material 100′ may be pattered to form the cavity104, wherein a die may be subsequently placed therein. The etch stoplayer 102 between the carrier material layers 100, 100′ may serve as anetch stop for the cavity 104 formation and may define a flat surface toplace the die on to. The cavity 104 as formed may comprise a bottomportion 101 an angled portion 105, and a top portion 107, wherein thetop portion comprises a portion of the etch stop layer 102.

In other embodiments, the cavity 104 may not be formed, and the bottomportion of the carrier material 100 may remain substantially flat, as inFIG. 1 a. In an embodiment, a die, such as a microelectronic die 106,for example, may be attached within the cavity 104 (FIG. 1 c). In anembodiment, the die 106 may comprise a thin die 106, and may comprise athickness of below about 150 microns. In an embodiment, the die 106 maybe attached to the top portion 107 of the cavity 104. In an embodiment,the die 106 may comprise at least one sidewall 108, a back side 111 andan active side 112. In an embodiment, the back side 111 of the die 106may be disposed directly on a portion of the etch stop layer 102 withinthe cavity 104. In some cases, an adhesive film (not shown) and/or anattach process may be used to attach the die 106 into the cavity 104 ofthe carrier material 100′.

In an embodiment, the adhesive film can be used as a permanent part of afinal package to protect the backside 111 of the die 106, to provide asurface for marking, and/or to manage any warpage that may occur withinthe die 106, for example. In an embodiment, the adhesive may comprise aback-side film (DBF) that may be applied to the back side 111 of the die106 prior to placement. The DBF may be filled with metallic particles(e.g, copper or silver), for example, to enhance conductivity whensubsequently connected to a heat spreader device, such as amicro-feature heat spreader, for example.

A dielectric material 110 may be formed on the carrier material 100′ andadjacent the die 106 that is in the cavity 104 of the carrier material100′ (FIG. 1 d). In an embodiment, the dielectric material 110 may beformed by a laminating process, for example. The dielectric material 110may be formed on the bottom portion 101 of the cavity 104, on the angledportion 105 of the cavity 104, and on a portion of the top portion 107of the cavity 104 of the carrier material 100′ that surrounds the die106. The dielectric material 110 may provide a level plane for asubsequent build-up process. In an embodiment, the carrier material 100′may be roughened prior to lamination to aid with adhesion to thedielectric material 110.

In an embodiment, vias may be formed in the dielectric material 112 in adie area landing of the die, wherein die pads, for example copper diepads, maybe exposed on the active side 112 of the die 106. In anembodiment, a semi-additive process (SAP) may be used to form die padinterconnect structures 112 on die pads of the die 106 and a first metallayer 114 may be formed on the dielectric material 110 adjacent the die106. Subsequent layers may then be formed using standard substrate SAPbuild-up processing, for example, wherein further dielectric layers 110′and metallization layers 114′ may be formed upon each other to form acoreless substrate portion 116 of a coreless package structure 120 byutilizing the buildup process (FIG. 10. In an embodiment, the corelesspackage structure 120 may comprise a BBUL coreless package structure120.

In an embodiment, a patterning material 118, such as a dielectricmaterial/resist material, may be formed on the carrier material 100(FIG. 1 g). For example, a dry film may be laminated and then patternedon the top layer of the carrier material 100, and then subtractiveetching/removal processing may be done to form a micro-feature structure122 that comprises a portion of the carrier material 100 and the etchstop layer 102 (FIG. 1 h). Thus, the micro-feature structure 122 isformed in-situ directly on the die 106 from the carrier material 100 ofthe coreless package structure 120. The coreless package substrate 120may further comprise interconnect structures 125, such as ball girdarray (BGA) balls, that may be attached to the package structure 120. Inan embodiment, the micro-feature structure 122 may comprise a height 126and a gap 128 between adjacent micro-feature structures 122, and maycomprise a heat spreader 122, for example.

In an embodiment, the microelectronic feature structures 122 that may bepattered and formed from the carrier material may include suchstructures as a heat spreader (as depicted in FIG. 1 h), Package onPackage (POP) land structures 122′, as depicted in FIG. 1 j, andinductor structures, for example. In some cases, the inductor structuresand the PoP land structures may be formed in non-die regions on a topsurface of the coreless package structure 120, and the inductorstructures and the PoP land structures may comprise the same material asthe micro-feature structure/heat spreader, since they are all formedfrom the carrier material. Since the micro-feature structure 122 isformed at the panel level, the throughput of the embodiments presentedherein is much faster than for prior art processes which attachmicro-electronic heat spreaders, for example, after the package ismanufactured. FIG. 1 i depicts a top view of the coreless packagestructure 120 of FIG. 1 i, wherein the micro-feature structure 122 isformed in situ from the carrier material on the die 106.

In an embodiment, the coreless package structure 120 may comprise afillet structure 124 of dielectric material 110 around the die 106,wherein the dielectric material 110 may surround the sidewall 108 andthe bottom 112 of the die 104, but wherein the dielectric material 110is absent on the back side 111 of the die 106 (FIG. 1 j). The filletstructure 124 may comprise an angled portion 121 of the dielectric 110that may be angled/raised in relation to a planar top portion 123 of thedielectric 110. The geometry of this fillet structure 124 can beoptimized to provide maximum reliability of the die/package. In anembodiment, the die 106 may be partially embedded into the corelesssubstrate 116. In another embodiment, the die 106 may be initiallydisposed on the flat portion of the material 100 (referring back to FIG.1 a), and may not be formed in a cavity (FIG. 1 k). In some embodiments,the backside 111 of the die 106 may be substantially coplanar with thetop portion 123 of the dielectric 110.

Benefits of the embodiments enable a new packaging architecture that canmeet design requirements for future mobile/handheld system on a chip(SoC) processors at roughly half the cost of current packagearchitectures. Various embodiments makes use of processes such as dryfilm lamination, patterning and subtractive etching to provide asolution for making a micro-channel based cooling solution, for example,on top of the die. Various embodiments serve for the addition of a veryeffective heat spreader by patterning part of the carrier that wouldnormally be etched away. Various embodiments enable patterning of acopper foil that may be part of a carrier for coreless BBUL packages.Prior art coreless BBUL packages typically target small dies (˜8×8 mm)in products with low power consumption. However, there is a need tobuild packages with larger die and higher power consumption, wherethermal cooling is expected to become a bigger problem.

Although the foregoing description has specified certain steps andmaterials that may be used in the method of the present invention, thoseskilled in the art will appreciate that many modifications andsubstitutions may be made. Accordingly, it is intended that all suchmodifications, alterations, substitutions and additions be considered tofall within the spirit and scope of the invention as defined by theappended claims. In addition, it is appreciated that variousmicroelectronic structures, such as package structures, are well knownin the art. Therefore, the Figures provided herein illustrate onlyportions of an exemplary microelectronic device that pertains to thepractice of the present invention. Thus the present invention is notlimited to the structures described herein.

What is claimed is:
 1. A structure comprising: a die disposed in apackage structure; a dielectric material adjacent the die; die padinterconnect structures in the die area; and at least one micro-featurestructure disposed on a top portion of the die, wherein the at least onemicro-feature structure is disposed directly on an etch stop materialdisposed directly on the die.
 2. The structure of claim 1 wherein the atleast one micro-feature structure comprises a copper material.
 3. Thestructure of claim 1 wherein the package structure comprises a portionof a coreless bumpless buildup package structure.
 4. The structure ofclaim 1 wherein the at least one micro-feature structure comprises aheat spreader.
 5. The structure of claim 2 wherein the die is partiallyembedded into the coreless substrate, and wherein the dielectricmaterial is formed along a portion of a sidewall of the die and not on atop portion of the die.
 6. The structure of claim 5 wherein the etchstop material comprises nickel.
 7. The structure of claim 3 wherein thepackage structure further comprises at least one of a PoP land structureand an inductor structure on a top surface of the package structure,wherein the at least one micro-channel structure and the at least onePoP land structure and inductor structure comprise the same material.